Video Processing Circuit for Liquid Crystal Panel Reverse Tilt Domain Prevention
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Solution Overview
Problem
The challenge in liquid crystal panels is the occurrence of reverse tilt domains due to horizontal electric fields, leading to display defects, which existing solutions either reduce aperture ratio or limit image brightness.
Innovation Solution
A video processing circuit that analyzes video signals to detect boundaries between pixels with different voltage levels and corrects applied voltages to adjacent pixels, preventing reverse tilt domains without altering the panel structure, thus maintaining aperture ratio and image brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new liquid crystal panel structure with light shielding layer conforming to pixel electrode is used, then reverse tilt domain is reduced, but aperture ratio decreases
Solution Approach 1:
A video processing circuit is introduced as an intermediary device between the video signal source and the liquid crystal panel. This circuit detects boundaries between pixels with different voltage levels and applies correction voltages to prevent reverse tilt domain formation, thereby solving the reliability issue without requiring structural modifications to the panel that would reduce aperture ratio.
2Reliability
If video signals with luminance value equal to or higher than preset value are clipped away, then reverse tilt domain is reduced, but brightness of displayed images is limited
Solution Approach 1:
Instead of globally clipping video signals which limits overall brightness, the invention applies local quality correction by detecting specific boundary regions between pixels and applying correction voltages only to pixels adjacent to these boundaries. This localized approach prevents reverse tilt domain formation without limiting the brightness of the overall displayed image.
3Manufacturing precision
If pixel pitch is narrowed for miniaturization and higher definition, then display resolution is improved, but horizontal electric field effect increases causing more reverse tilt domain
Solution Approach 1:
The video processing circuit implements a feedback mechanism by analyzing the video signal to detect boundaries between pixels with different voltage levels, then applying correction voltages based on this detected information. This feedback approach dynamically compensates for the increased horizontal electric field effect caused by narrowed pixel pitch, allowing high-resolution displays without suffering from reverse tilt domain issues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents reverse tilt domains without decreasing aperture ratio or limiting image brightness, allowing for stable display performance across various liquid crystal panel configurations.
Implementation Method 1
When a voltage corresponding to a gradation level is applied and held between the pixel electrode and the common electrode, the alignment state of the liquid crystal is defined for each pixel, whereby transmittance or reflectance is controlled
Implementation Method 2
a liquid crystal is interposed between the pixel electrodes and the common electrode
Implementation Method 3
the effect of an electric field which is generated between the adjacent pixel electrodes, namely an electric field in the direction parallel (horizontal) to the substrate surface has become unignorable
Implementation Method 4
when a horizontal electric field is applied to a liquid crystal that is designed to be driven by a vertical electric field such as in a VA (Vertical Alignment) or TN (Twisted Nematic)-mode liquid crystal, there is a problem in that alignment defects (namely, reverse tilt domain) occur in the liquid crystal
Data Source
AI summary
A video processing circuit used in a liquid crystal panel, includes: a first boundary detector that analyzes a video signal of a present frame to detect a boundary between a first pixel and a second pixel; a second boundary detector that analyzes a video signal of a frame one frame before the present frame to detect a boundary between the first pixel and the second pixel; a third boundary detector that detects a risk boundary that is determined by a tilt azimuth of the liquid crystal; and a correction portion that corrects an applied voltage to a liquid crystal device corresponding to a first pixel from the applied voltage to a liquid crystal device corresponding to the first pixel to a third voltage or higher, when the applied voltage specified by the video signal input to the first pixel is lower than the third voltage.